TABLE 2.

Diseases associated with gut microbiota abnormalities.

Disease	Features	References
Irritable bowel syndrome	An abundance of Firmicutes and a decrease in Bacteroidetes.	Kennedy et al., 2014
Type 1 diabetes	In genetically predisposed individuals, autoimmune against pancreatic b-cells. Deficient development or alteration of the microbiota may contribute to dysfunctional immunity with the devastation of autoimmune b-cells and increased leakiness of the intestinal epithelial barrier. Variability of microbiomes reduced.	Dunne et al., 2014
Asthma	Outbreaks of Chlamydophila pneumonia during bronchitis and pneumonia development affect the airway microbiome. Gut microbiota is influenced by the introduction of microbiota to the environment, particularly in early life, which helps immune function growth and the development of defending against allergic sensitization.	Huang and Boushey, 2015
Food-borne pathogens and food poisoning	Opportunistic pathogens (Campylobacter, Salmonella, Escherichia coli, Shigella, etc.) disturb the microbiome’s balance leading to dysbiosis.	Josephs-Spaulding et al., 2016
Malnutrition	Decrease or missing species that either process food categories efficiently or produce vitamins may reduce the absorption of nutrients. An overabundance of Enterobacteriaceae can lead to epithelial damage, diarrhea, and limited absorption of nutrients.	Kane et al., 2015
Depression	In physiological systems, Bifidobacterium infantis, generally found in infants’ gastrointestinal tract and administered probiotic drugs, can have antidepressant effects.	Evrensel and Ceylan, 2015
Anxiety	Oral administration of Campylobacter jejuni subclinical doses in murine models induced anxiety-like behavior without stimulating immunity. In a marine model, the Lactobacillus and Bifidobacterium may act as an anxiolytic influencer.	Schnorr and Bachner, 2016